This is not true, some times long term investors are those who make more money.
Think investing in BTC when it was nothing...
Today you can invest to a really good ICO with long terms goals
Long term investors really make a good profit, but as what tings now are happening, alts is being push back due to bitcoin's persistent rise for several days now. I lost already more than 50% of my portfolio in some alts but still I am hopeful it will recover soon after correction.